1. Field of the Invention
The present invention relates generally to methods for formation of atomic ridges.
2. Description of the Prior Art
Metal-semiconductor growth systems that exhibit one-dimensional (1 -D) structures on the nanometer scale have lately been of interest, particularly those that form nanowires. Usually such structures have been grown by depositing metals on periodically stepped (or vicinal) surfaces. However, this step growth method has the disadvantage that the steps are not atomically straight, and that the deposited metal must preferentially nucleate at the step edges.
1-D structures also be grown using other types of surface morphologies other than steps. A number of high-index, xe2x80x9ctiltedxe2x80x9d silicon surfaces possess unique morphologies not found on their low-index counterparts. For example, the recently discovered surface of Si(5 5 12) is oriented 30.5 away from (001) towards (111) and forms a single-domain, planar reconstruction composed of row-like structures. It is known that group-III metals cause major faceting of this surface, see Baski et al., Surf. Sci. 423, L265-270 (1999). In contrast, the deposition and annealing of noble metals on Si(5 5 12) may lead to the formation of nanowire arrays.
It is therefore an object of the present invention to provide a method for forming regularly spaced atomic ridges on a silicon wafer with a variety of spacings (or pitch).
It is another object of the present invention to provide a method for forming regularly spaced Au and other metal nanowires, as well as either positive or negative lithographic etch masks, for forming a variety of useful structures on particular crystal surfaces of Si and other semiconductors.
According to a first broad aspect of the present invention, there is provided a method for producing atomic ridges on a substrate comprising: depositing a first metal on a substrate; heating the substrate to form initial nanowires of the first metal on the substrate; depositing a second metal on the initial nanowires of the first metal to form thickened nanowires that are more resistant to etching than the initial nanowires; and etching the substrate to form atomic ridges separated by grooves having a pitch of 0.94 to 5.35 nm.
According to a second broad aspect of the invention, there is provided a method for producing Au nanowires on a substrate comprising: depositing Au on a substrate; heating said substrate to form a plurality of Au nanowires on the substrate wherein at least two adjacent nanowires of the plurality of Au nanowires are at a pitch of 2.51 to 3.45 nm.
Other objects and features of the present invention will be apparent from the following detailed description of the preferred embodiment.